Participation of Cytochromes in the Respiration of the Aroid Spadix.

Yocum, C. S.; Hackett, David P.

doi:10.1104/pp.32.3.186

Cited by 91 publications

(58 citation statements)

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“…This suiggestion is stupported by the observation that fruiits evolve less ethylelne (6) 4 and(i 7 show I/Vn3 to be independent of (S) so that the behavior of the tis.sue at all inifinite concenitrationi of ethylene (1/A -0) caln be l)redicted by the low-er dashed line. Kg, the Michaelis-Menlteni constanit for 0,, has a value of 40 ju.m (2.8 % in the gas phase), which is comparable tc v-alues reported for n-iany other oxidases (33) but considerably higher than that for cytochrome oxidase (33). at inhibitor concenitrationis which retarded growth and respiration by more than 50 % the sensitivity to ethylene remained unchanged and the double reciprocal plot was indistinguishable from the control curve (fig 4, AIR).…”

Section: Discussionsupporting

confidence: 66%

Molecular Requirements for the Biological Activity of Ethylene

1967

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Summary. The molecular requirements for ethylene action were investigated using the pea straight growth test. Biological activity requires an unsaturated bond adjacent to a terminal carbon atom, is inversely related to molecular size, and is decreased by substitutions which lower the electron densitv in the unsaturated position. Evidence is presented that ethylene binds to a metal containing receptor site. 002 is a competitive inhibitor of ethylene action, and prevents high concentrations of auxin (which stimulate ethylene formation) from retarding the elongation of etiolated pea stem sections. It is suggested that CO2 delays fruit ripening by displacing the ripening hormone, ethylene, from its receptor site. Binding of ethylene to the receptor site is also impeded when the 02 concentration is lowered, and this may explain why fruit ripening is delayed at low O. tensions.Several gases in addition to ethylene elicit the triple response in etiolated seedlings, and the concentration of each requlired to produce a just discernible effect has been determined (9, 25). Included are propylene, butylene (isomer unknown), acetylene, and CO. Since these vapors also substitute for ethylene in causing epinasty (9, 10), fruit ripening (11,27), and other effects (8,9, 29), it would appear that the molecular requirements for biological action are similar in each case. We have attempted to delineate these requirements using as an assay for ethylene action the effect which the gas has on the growth and tropistic behavior of etiolated pea stem sections. Materials and MethodsPeas (Pisum sativum, var. Alaska) were soaked in water for 5 hours and germinated in moist vermiculite. The seedlings developed in darkness at 230 receiving an occasional exposure to dim red illumination, and were used on the seventh day. Sections 10 mm long were cut from the third internode just below the leaf hook and incubated in a medium containing 1 uM indole-3-acetic acid (IAA), 2 % sucrose (w/v), 0.05 M potassium phosphate buffer (pH 6.8), and 5 ptM CoCl in glass distilled water. Ten ml of media and 10 sections were placed in a 125 ml Erlenmeyer flask, this was sealed with a vaccine cap, the gas phase ad-'This investigation was supported by research grants EF-00214 and EF40078&2 from the United States Public Health Service, Division of Environmental Engineering and Food Protection, and was carried out while S. P. Bukrg was the recipient of Career Research DevelopmentAward 1-K3-GM-6871 from the USPHS. justed as described below, and the tissue slowly shaken at 230 in the dark. After 3 hours the sections were visually scored in red light for curvature and 15 hours later the gas phase was analyzed by gas chromatography before the tissue was removed, blotted dry, weighed and measured. Details of the procedure have been published elsewhere (4). Gas Chromatography and Preparation of GasM&ixtures. All gases were chromatographed on a 3 foot alumina column to determine whether ethylene or other low molecular weight contaminants were present. The instrument, a Perk...

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Section: Discussionsupporting

confidence: 66%

Molecular Requirements for the Biological Activity of Ethylene

1967

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“…2 This work was supported by a grant from the Nationtal Science Foundation. that terminal respiration in the Aroid spadix, like that in other plant tissues (11), is mediated by the particle-bound cytochrome system is supported by spectrophotometric observations of the intact tissue (25). m,/ at 450 mfA, and 1 mnu at 550 mu.…”

mentioning

confidence: 52%

“…In The difference spectra show clearly the participation of cytochromes of the a, b, and c types in the reaction of skunk cabbage mitochondria with oxygen. The positions of the peaks in the a and Soret regions, the reaction with CO, and the previous demonstrations of evtochrome oxidase activity (12,22,25) all suggest that a typical cytochrome a-a3 complex is functioning in these particles. As yet, no other atylpe oxidase has been found.…”

Section: Resultsmentioning

confidence: 95%

“…Although it was concluded that a flavoprotein serves as the terminal oxidase in such tissues (15), it is now clear that they contain high concentrations of cytochromes which probably function in respiration (2,4,12,20,22,25). Following the demonstration that isolated spadix mitochondria oxidize Krebs cycle acids very rapidly (13), it was shown that most of the cytochrome components are also localized on these particles (2,4,12).…”

mentioning

confidence: 99%

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Oxidative Phosphorylation and Functional Cytochromes in Skunk Cabbage Mitochondria.

Hackett

Haas

1958

Plant Physiol.

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“…Interest in respiration has centred around the presence, characteristics and role of inhibitor stimulated oxygen uptake a property which is widespread among the algae. Despite numerous studies [2][3][4][5][6][7][8] the mechanism of inhibitor stimulated respiration is unknown.…”

Section: Introductionmentioning

confidence: 99%